A conventional automatic visual acuity testing device which has been proposed shows optotypes to an examinee and automatically tests a visual acuity of the examinee (see Japanese patent application (publication No. H09-1187423, for instance).
FIG. 5 is a perspective view showing appearances of a conventional structure of such an automatic visual acuity testing device. A reference numeral 200 is an optotype portion for showing an optotype, such as a Landolt ring, which is inside a housing 201, and a reference numeral 202 is a test window through which an examinee looks into the optotype portion 200, and a reference numeral 203 is a joystick lever to be operated by an examinee for inputting results of recognition of the optotypes. This kind of the automatic visual acuity testing device has such a structure that input of judgment results of optotypes by an examinee through an operation of the joystick lever 203 in a state that the examinees looks into the optotype portion 200 through the test window 202 causes output of tested results through a printer
When suffering from an ophthalmic disease, such as glaucoma and diabetic retinopathy, it is known that a person has a narrow visual field or a lacked visual field. For these reasons, visual field devices having various structures have been proposed as devices for finding such diseases (see Japanese patent application the publication number of which is 2002-272685).
FIG. 14 is a typical view showing a structure of a conventional visual field device. In FIG. 14, a reference numeral 400 denotes a projection optical system for projecting stimuli A, and a reference numeral 401 denotes a visual field dome in the shape of a semi-sphere for projecting stimuli. And, a reference numeral 403 is a response switch to be operated by an examinee.
When starting the visual field device in such a state that an examinee fixates a fixation point inside the visual field dome 401, the projection optical system 400 successively displays stimuli A at various positions of the visual field dome 401. An examinee operates the response switch 403 when perceiving the stimulus A, but does not operate when not perceiving. The visual field of an examinee can be measured from displayed positions of the stimuli A.
When an examinee can not immediately perceive too small optotype in the above-mentioned automatic visual acuity testing device, the examinee may operate the joystick lever 203 after taking a longer time, hesitating to respond. In addition, an examinee may give a wrong answer due to error operation of the joystick lever 203 even if the examinee fully recognizes the optotype. Problems remain if the visual acuity is determined only by right or wrong answer of the result of perception of optotype in such cases.
Generally, an examinee immediately operates the response switch 403 when clearly perceiving the stimulus A and slowly operates the response switch 403, hesitating to answer when faintly perceiving the stimulus in the above-mentioned visual field device. A conventional device measures a visual field without considering a time till the operation of the response switch 403, so that proceeding of the examination is not effective.
The object of the invention is to provide a visual acuity testing device for accurately testing a visual acuity, and a visual acuity testing equipment with the visual acuity testing devices.
Besides, the object of the invention is to provide a visual field device for effectively testing a visual field.